The HN forum system and possible improvements

1. When you respond to a person, that person has no idea unless they check their comment tree. Is that right? If so, why not give a notification? Make it like reddit.

2. There are certain topics that get brought up pretty frequently and it seems like the conversation starts from ground zero nearly every time. And this forum disables commenting after a certain period. Doesn't that just encourage starting a new thread and having the same conversation again? Some forums deal with this by making stickies.